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Calendar of Physics Talks Vienna
| Micromanipulation, quantum metrology and vacuum forces: a unified perspective based on the scattering matrix (Vienna Theory Lunch Seminar) |
| Speaker: | Lukas Rachbauer (TU Wien) |
| Abstract: | We introduce the quantum Wigner-Smith (QWS) operator, a Hermitian operator describing the interaction between the spatial as well as the quantum degrees of freedom of light and a local classical parameter of a linear, but otherwise arbitrarily complex scattering medium through which the light propagates. The QWS operator builds a bridge between quantum micromanipulation, vacuum forces and quantum metrology on the one side, and the formalism of classical scattering matrices, which are experimentally measurable in a noninvasive manner, on the other side. [...]
[[part of the "Vienna Theory Lunch Seminar, see https://lunch-seminar.univie.ac.at, please find also the full abstract on the web page]] |
| Date: | Tue, 14.11.2023 |
| Time: | 12:30 |
| Duration: | 75 min |
| Location: | TU Wien: Wiedner Hauptstr. 8-10, yellow area, 10th floor, seminar room DB10E11 |
| Contact: | Florian Lindenbauer |
| Cosmic Imprints of Quantum Gravity: Insights from the Swampland Program |
| Speaker: | Marco Scalisi (Max Planck Institute for Physics, Munich) |
| Abstract: | Common lore suggests that effects of quantum gravity are difficult to unravel. The Planck scale is in fact about 15 orders of magnitude above the highest energy reached on Earth, namely at the Large Hadron Collider. The Swampland program suggests instead that the quantum gravity cut-off can decrease thus making quantum gravity effects accessible at energies lower than the Planck scale. In this talk, I will first review some basics of Swampland program; I will then concretely show how the quantum gravity cut-off can drop in certain situations; I will finally explore the implications of this fact for cosmology. |
| Date: | Tue, 14.11.2023 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Sem. R. DB gelb 03 - TU Wien Freihaus (Wiedner Hauptstrasse 8, 3rd floor, yellow tower) |
| Contact: | Stefan Fredenhagen, Tung Tran, Adrien Fiorucci |
| Weyl channels for multipartite systems |
| Speaker: | José Alfredo de León (Instituto de FÃsica, Universidad Nacional Autónoma de México) |
| Abstract: | Quantum channels describe the unitary and non-unitary evolution of quantum systems. We study a generalization of the concept of Pauli maps to the case of multipartite high dimensional quantum systems through the use of the Weyl operators. The condition for such maps to be valid quantum channels, i.e. complete positivity, is derived in terms of Fourier transform matrices. From these conditions, we find the extreme points of this set of channels and identify an elegant algebraic structure nested within them. In turn, this allows us to expand upon the concept of âcomponent erasing channelsâ. We show that these channels are completely characterized by elements drawn of finite cyclic groups.
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| Date: | Wed, 15.11.2023 |
| Time: | 11:00 |
| Duration: | 45 min |
| Location: | Seminarroom ZE 01-1 |
| Contact: | Marcus Huber |
| From the Weyl-Schrödinger connection to the accelerating Universe - extending Einstein's gravity via a length preserving nonmetricity |
| Speaker: | Tiberiu Harko (Babes-Bolyai U) |
| Abstract: | One of the important extensions of Riemann geometry is Weyl geometry, which is essentially based on the ideas of conformal invariance and nonmetricity. A similar non-Riemannian geometry was proposed by Erwin Schrödinger in the late 1940s, in a geometry which is simpler, and (probably) more elegant than the Weyl geometry. Even it contains nonmetricity, the Schrödinger connection preserves the length of vectors under parallel transport,and thus seems to be more physical than the Weyl connection. Interestingly enough, Schrödinger's approach did not attract much interest in the field of gravitational physics.It is the goal of the present talk to reconsider the Schrödinger geometry as a potential candidate for a gravitational theory extending standard general relativity. We consider a gravitational action constructed from a length preserving non-metricity, in the absence of torsion . . . . |
| Date: | Wed, 15.11.2023 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Waehringer StraÃe 17, 2. Stock |
| Contact: | P. Chrusciel, D. Fajman |
| Symplectic structure of the Jackiw-Teitelboim gravity |
| Speaker: | Anton Alekseev (University of Geneva) |
| Abstract: | The Jackiw-Teitelboim (JT) gravity has recently attracted a lot attention because it gives a simple and yet nontrivial example of holographic duality.
In this talk, we discuss the symplectic structure associated to the JT gravity. This topic was pioneered by Saad-Shenker-Stanford and by Stanford-Witten.
We will argue that the infinite dimensional Teichmüller space associated to a hyperbolic surface with boundary at infinity carries a canonical symplectic structure which arises through Hamiltonian reduction.
This reduction procedure is rather standard in the bulk and it has novel features at the boundary of the surface.
In particular, the Teichmüller space carries an action of the diffeomorphism group of the boundary with a non vanishing Virasoro central charge.
The talk is based on a joint work in progress with Eckhard Meinrenken. |
| Date: | Thu, 16.11.2023 |
| Time: | 13:15 |
| Duration: | 60 min |
| Location: | Erwin Schroedinger Institute for Mathematics and Physics, Schroedinger lecture hall - Boltzmanngasse 9, 2nd floor |
| Contact: | S. Fredenhagen, H. Steinacker |
| Cosmological models: Hierarchies of asymptotic behaviour |
| Speaker: | Helmut Friedrich (AEI Potsdam) |
| Abstract: | De Sitter space-time is a geodesically complete,conformally flat, spatially compact solution to the Einstein-λ-vacuum equations with cosmological constant λ that admits smooth conformal boundaries ${\cal J}^{\pm}$ at future and past time-like infinity.Data sufficiently close to de Sitter data develop into solutions to the Einstein-λ-vacuum equations that admit smooth conformal boundaries as well.These solutions extend,as solutions to the conformal Einstein equations,beyond these boundaries where they define again solutions to the Einstein-λ-vacuum equations. Gravitational radiation, i.e. perturbations to the conformal Weyl tensor,travels unimpeded across ${\cal J}^{\pm}$ into the extended domain. We discuss our interest in this phenomenon and the question to what extent it generalizes to the future developments of solutions to the Einstein-λ equations coupled to various matter fields. |
| Date: | Thu, 16.11.2023 |
| Time: | 15:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Waehringer StraÃe 17, 2. Stock |
| Contact: | P. Chrusciel, D. Fajman |
| New platforms for quantum sensing and quantum computing |
| Speaker: | Nathalie P. de Leon (Princeton University) |
| Abstract: | The nitrogen vacancy (NV) center in diamond exhibits spin-dependent fluorescence and long spin coherence times under ambient conditions, enabling applications in quantum information processing and sensing. NV centers near the surface can have strong interactions with external materials and spins, enabling new forms of nanoscale spectroscopy. However, NV spin coherence degrades within 100 nanometers of the surface, suggesting that diamond surfaces are plagued with ubiquitous defects. I will describe our recent efforts to correlate direct materials characterization with single spin measurements to devise methods to stabilize highly coherent NV centers within nanometers of the surface. We deploy these coherent shallow NV centers for a new nanoscale sensing technique, whereby we use covariance measurements of two or more NV centers to measure two-point magnetic field correlators.
Our approa |
| Date: | Fri, 17.11.2023 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Andrew Kanagin |
| QCD at high energies: Wilson lines in the CGC and jets |
| Speaker: | Heribert Weigert (University of Cape Town) |
| Abstract: | I will provide an introduction to the ideas behind the Color Glass Condensate and the JIMWLK evolution equation.
I will introduce a counterpart to structure functions for Wilson line correlators and provide some insight into the
diverse role of color singlets in evolution equations involving Wilson line correlators.
To wit, these structures also occur in the evolution of certain jet observables.
I will further explore the structural relationship of evolution equations in the CGC and jet context (JIMWLK vs BMS-W) using a conformal map.
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| Date: | Fri, 17.11.2023 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Kurt-Goedel-Hoersaal, Fakultaet fuer Physik, Boltzmanngasse 5, Erdgeschoss |
| Contact: | A. Hoang, M. Procura, S. Plaetzer |
| Power corrections to collider observables |
| Speaker: | Kirill Melnikov (KIT) |
| Abstract: | I will present the recent attempts to optimize the computation of power corrections to collider
observables in the context of renormalon calculus. Examples related to top quark production processes
at a hadron collider and jet production in electron-positron collisions will be discussed.
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| Date: | Fri, 17.11.2023 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultaet fuer Physik, Josef Stefan-HS, Boltzmanngasse 5, 3. Stock |
| Contact: | A. Hoang, M. Procura |
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